It is desirable to have thermosettable compositions which form polymeric materials stable at elevated temperatures and useful in making composites, adhesives, and coatings. Polyimides are known to offer desirable high temperature properties. Many polyimide compositions, however, are based upon condensation chemistry, which tends to result in the formation of voids in the cured polymeric material. Maleimides, on the other hand, provide void-free cross-linked polymeric materials which exhibit good high temperature stability.
Zahir et al, in U.S. Pat. No. 4,100,140, disclose the manufacture of cross-linked Polymers by reacting polymaleimides with alkenylphenols or alkenylphenol ethers. According to that patent, the reaction mixtures for these polymers are of lower viscosity than the starting mixtures for similar prior art polymers and thus are suitable for the manufacture of complex castings. In U.S. Pat. No. 4,130,600, Zahir et al disclose a thermosetting mixture which contains polymaleimides, epoxide compounds having at least one allyl group and, optionally, curing agents for the epoxide compounds and/or curing accelerators for epoxide resin mixtures. In U.S. Pat. No. 4,127,615, Zahir et al disclosed a thermosetting mixture which contains polymaleimides, alkenylphenols and/or alkenylphenol ethers, epoxide compounds with or without allyl groups and, optionally, curing accelerators for epoxide resins. According to Zahir et al, the compositions comprising epoxide compounds yield thermosetting polymers which have high dimensional stability at high temperatures. While Zahir et al have described their compositions as storage-stable, such compositions have less than desirable storage stability since the compositions contain free epoxide groups which react with, e.g., curing agents or phenol which may be present in the composition encouraged by the accelerators which are generally present in the composition. We also have found that embodiments of these compositions of Zahir et al tend to be brittle, i.e., lack the toughness and flexibility desired for such materials. The present invention composition overcomes the disadvantages of such prior art compositions.